He minted coins called Mananka and constructed the palace of Managriha for himself which later became a center of administration of the Licchavi kings.

[3][4] Mandev's father died when he was young and he was crowned as the king in his early age.

His mother Rajyabati, upon her husband's death, chose to assist her son in ruling the kingdom rather than going Sati.

[4] After he ascended the throne, the Thakuri governors of the eastern provinces tried to revolt with the aim of gaining independence from the Licchavi rule.

[4][5] After crushing the rebels, he, along with his maternal uncle, marched towards west and conquered Mallapuri, Nabalpur and various other tiny states.